Interannual variation in the reproductive cycle of the New Zealand snapper Pagrus auratus (Bloch & Schneider) (Sparidae)


*Author to whom correspondence should be addressed at Zoology Department, University of Otago, P.O. Box 56, Dunedin. New Zealand.


Changes in reproductive condition in the New Zealand snapper Pagrus auratus (Bloch & Schneider) were monitored in a wild population over three successive years. Recrudescence occurred in spring with spawning beginning in October and continuing for 3 to 5 months. The initiation of spawning varied by up to 3 weeks and was associated with sea surface temperatures of 15–16° C. Theconclusion of spawning was associated with temperatures of 19–21° C but showed greater interannual variation than the onset of spawning. Changes in the gonadosomatic index were accompanied by parallel changes in hepatosomatic index in females but not males, reflecting the role of the liver in vitellogenesis in females.